'Arrow': Katie Cassidy Returning as Series Regular — With a Twist

After Cassidy's character Laurel Lance was tragically killed off in season four, the actress is returning to the CW series as her Earth-2 doppelgänger Black Siren.

Katie Cassidy is returning to the DC TV family.

After her character Laurel Lance was shockingly killed off Arrow in season four, Cassidy is coming back to the CW series as Laurel's evil Earth-2 doppelgänger Black Siren, The Hollywood Reporter has learned. The actress will appear in the final two episodes of season five before returning as a series regular for season six.

"One of the things that most excites us about Arrow is that we go where the story takes us," executive producer Marc Guggenheim said in a statement. "Last year, the story took us to the tragic death of Laurel Lance. This year, our midseason finale reintroduced us to Laurel’s doppelgänger, Black Siren. We were so taken by Katie’s fearless interpretation of this character that we knew her story was not yet finished. We couldn’t be more thrilled to welcome Katie back to Arrow as Black Siren, though as her appearances on Arrow and Legends of Tomorrow this season show, she never really left the family."

Cassidy first made her debut as Laurel's evil metahuman twin from another universe on The Flash last season, where she was caught and imprisoned by Barry Allen (Grant Gustin). She was released from the STAR Labs pipeline prison by Arrow season five villain Prometheus (Josh Segarra) to cause emotional turmoil for Oliver Queen (Stephen Amell), as Oliver thought Laurel was miraculously resurrected by her time-traveling sister Sara Lance (Caity Lotz) on Legends of Tomorrow. When Oliver finally learned the truth, he caught her again with the help of Felicity (Emily Bett Rickards) and Curtis (Echo Kellum) and handed her over to ARGUS for custody.

Black Siren's full-time return is a big deal, since Oliver still had hope that he could help her find redemption and become a hero when he gave her over to ARGUS. While it's been proven time and time again that multiverse doppelgängers are not the same people, Oliver still blames himself for Laurel's death at the hands of Damien Darhk (Neil McDonough). Subsequently, he hoped that by rehabilitating Black Siren, he could finally get some peace of mind.

It also means that the Arrow showrunners are living up to their word. Back in the season four premiere, the showrunners introduced a season-long mystery by showing a funeral without revealing who was in the grave. When that storyline was first introduced, producers were outspoken about how they didn't know who was going to end up in the grave. When it came time to kill off a character to make good on that mystery, they picked Laurel despite her long DC Comics history as the Black Canary and Oliver's love interest.

"Arrow is always a show that's evolving. Every character arguably except for the Arrow is fair game," Guggenheim has previously said. "We started off [that season] with a promise of a death, and when we worked our way through our various creative choices, we realized that the thing that will give us the most pop going into the end of the season, going into next season, unfortunately would be Laurel."

But Guggenheim, along with executive producer Wendy Mericle, also promised that that would not be the last time Cassidy appeared in The CW's larger four-show DC universe that includes The Flash, Supergirl and Legends of Tomorrow. So far, she has reprised her role of Earth-1 Laurel Lance on CW Seed's animated series Vixen, introduced her Earth-2 doppelgänger Black Siren on The Flash and is now returning to Arrow.

"Not getting a chance to work with Katie day in and day out is tempered by the fact that we now live in a world and universe where there is resurrection, parallel earths, time travel and flashbacks," Guggenheim said. "We have all these different ways of keeping Katie in the Arrow-verse family. Death does not mean goodbye on any of these shows."

Cassidy is repped by CAA, Anonymous Content and Jackoway Tyerman.

Arrow airs Wednesdays at 8 p.m. ET/PT on The CW. What do you think of her return?